• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.509-516
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• 2015

We investigated the reduction leaching process of manganese dioxide ore using black locust as reductant in sulfuric acid solution. The effect of parameters on the leaching efficiency of manganese was the primary focus. Experimental results indicate that manganese leaching efficiency of 97.57% was achieved under the optimal conditions: weight ratio of black locust to manganese dioxide ore (WT) of 4:10, ore particle size of $63{\mu}m$, $1.7mol{\cdot}L^{-1}\;H_2SO_4$, liquid to solid ratio (L/S) of 5:1, leaching time of 8 h, leaching temperature of 368 K and agitation rate of $400r{\cdot}min^{-1}$. The leaching rate of manganese, based on the shrinking core model, was found to be controlled by inner diffusion through the ash/inert layer composed of associated minerals. The activation energy of reductive leaching is $17.81kJ{\cdot}mol^{-1}$. To conclude the reaction mechanism, XRD analysis of leached ore residue indicates manganese compounds disappear; FTIR characterization of leached residue of black locust sawdust shows hemicellulose and cellulose disappear after the leaching process.

• Journal of the Korean Chemical Society
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• v.41 no.10
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• pp.541-546
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• 1997

Manganese dioxide may react with silicon tetrachloride to form manganese(Ⅳ) oxodichloride which reacts subsequently with another molecule of silicon tetrachloride leading to manganese tetrachloride eventually in chlorinated solvents. This in situ generated manganese(Ⅳ) oxodichloride or manganese tetrachloride were found to be very effective for the chlorination of a wide variety of alcohols to the corresponding chlorides. Primary, secondary and benzylic alcohols were converted into corresponding chlorides when treated with silicon tetrachloride in the presence of manganese dioxide at room temperature.

• Proceedings of the KAIS Fall Conference
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• 2001.11a
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• pp.79-84
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• 2001

본 논문에서는 리튬전지의 Cathode active material로 CMD(chemical manganese dioxide)를 사용하여 현재 사용중인 EMD(electrolytic manganese dioxide)와 공정 수율 및 특성과 방전 성능을 비교함으로써 새로운 cathode active material.로의 적용 가능성을 확인하기 위함이다.

• Journal of the Korean Applied Science and Technology
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• v.17 no.1
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• pp.49-53
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• 2000

For decompose carbon dioxide, manganese oxide was synthesized with $0.25M-MnSO_{4}{\cdot}nH_{2}O$ and 0.5M-NaOH by coprecipitation. We made magnetite deoxidized manganese oxide by hydrogen reduction for 1hour at $330^{\circ}C$. We investigated characteristics of catalyst, hydrogen reduction degree and decomposition rate of carbon dioxide. The structure of the hausmannite certified spinel type. The specific surface area of synthesized hausmannite and deoxidized hausmannite were $22.36m^{2}/g$, $33.56m^{2}/g$ respectively. The decomposition rate of $CO_{2}$ of deoxidized hausmannite was 57%.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.369-373
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• 2002

The liquid phase oxidation of p-xylene has been carried out with oxygen-enriched gas, and the manganese component was precipitated probably via over-oxidation to $Mn^{4+}$. The precipitation increased with rising oxygen concentration in the reaction gas and occurred mainly in the later part of the oxidation. The activity of the reaction decreased, and the blackening of the product and side reactions to carbon dioxide increased with the degree of precipitation. Precipitation can be decreased with the addition of metal ions, such as cerium, chromium and iron.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.460-464
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• 2013

A series of Mn compound were prepared by seed-assisted method. The seed used in this reaction was manufactured by calcination of $MnCO_3$ at various temperatures and effects of the calcination temperature on seed-assisted reaction were investigated. With increase of the calcination temperature, CMD (${\gamma}-MnO_2$) was recovered after seed-assisted reactions. LMO used as cathode active material in the Li-ion batteries were synthesized from Mn source obtained in the seed-assisted reaction and the electrochemical properties (rate capability, cycle life performance and specific capacity) of the LMO were investigated. The LMO synthesized from the CMD which is obtained by the reaction with seed prepared by calcination of $MnCO_3$ more than $350^{\circ}C$ shown good electrochemical properties.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.552-553
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• 2005

In order to improve energy efficiency in the dilute trichloroethylene removal using the nonthermal plasma process, the barrier discharge treatment combined with manganese dioxide was experimentally studied. Reaction kinetics in this process was studied on the basis of final byproducts distribution. Decomposition efficiency was improved to about 99% at the specific energy 40J/L with passing through manganese dioxide. C=C $\pi$ bond cleavage in TCE gave DCAC (single bond, C-C) through oxidation reaction during the barrier discharge plasma treatment. Those DCAC were broken easily in the subsequent catalytic reaction due to the weak bonding energy about 3 ~ 4 eV compared with the double bonding energy in TCE molecules. Oxidation byproducts of DCAC and TCAA from TCE decomposition are generated from the barrier discharge plasma treatment and catalytic surface chemical reaction, respectively. Complete oxidation of TCE into $CO_X$ is required to about 400J/L.

• Resources Recycling
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• v.6 no.4
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• pp.11-16
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• 1997

The wastewater resulted from the process of developing and fuing for x-ray film manufachlring contains a lot of silvercomponent. The average concentation of silver-component is about 1,500 mgA. The wastewater contained silver-component is toxic when it is discharged to the natural ecosystem. So that we must to do pretreatment of wastewater prior to discharge. There are electrolysis. chemical precipitation, and metallic replacement as conventional lreabent proccss of fixer wastewater of x-ray film. Adsorption of silver-component in x-ray fkcr wastewater was carricd out this study. 'Ille manganese dioxide (MDO) reagent and the recovered manganese dioxide (RMDO) from the waste dry-cell were used for adsarbents. Adsorption of silvercomponent was wrried out at the batch and continuous type experimental equipment. The adsorption experiment results were obtained bom silver-component have some diifcrences according to adsorhents. The adsorption results of manganese dioxide reagent (MDO) were better ihan those of waste dry-ccU (RMDO), but the manganese dloxide recovered fmm waste dry-cell (RMDO) will be able la recognized as good adsorbent too.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2488-2492
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• 2010

A method is described for the determination of the Po nuclides in a water sample. After the Po nuclides were purified from interfering elements in a water sample using a manganese dioxide precipitation followed by a solvent extraction method, the Po nuclides were deposited onto the silver plate. A large volume of the water sample was effectively pretreated with manganese dioxide precipitation method. To determine the optimum conditions for plating Po, the effects of the pH, volume, temperature and time on the Po deposition were investigated in hydrochloric acid solution. The investigated determination method of Po nuclides with solvent extraction was applied to a tap water sample.

• Journal of the Korean Chemical Society
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• v.15 no.5
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• pp.241-245
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• 1971

Endothermic peak of transformation of ${\gamma}-MnO_2$ was obviously shown by differential heating curve in the present study, and the transformation temperature was different from other modification. ${\gamma}-MnO_2$ carried out to analyze exclusively, by means of the half area method in corresponding endothermic peak of differential heating curve. ${\alpha}-\;and\;{$beta}-MnO_2$ (Pyrolusite) containing in sample about 75% is interfered about ${\pm}$10% of the relative error, and while those of below 50% is interfered about ${\pm}$5%.